The present invention relates to the electronic detection of darts or other missiles which are embedded in discrete scoring segments or areas of a target, such as in a conventional fiber or bristle dart board.
Various approaches have been taken in the past to automatically detect and electrically score games which employ a projectile which is to be propelled toward some form of target having areas denominated in different scores. One example of such game is the game of darts in which a dart is thrown at a dart board having plural segments or areas of differing scores. Depending upon which segment the dart becomes embedded in, the game player is credited with the score for that area.
One prior system in which the location of the dart is automatically detected and electrically scored is shown for example in U.S. Pat. No. 4,057,251 (JONES et al.). In that system the scoring segments are formed by a plurality of movable plates having holes therein. When the tip of a thrown dart enters one of the holes in a plate, the plate is mechanically displaced by the momentum of the dart so as to close and actuate an electrical switch to detect and locate the position of the dart on the dart board. However, these moveable mechanical plate and switch systems have a number of disadvantages including complexity, reliability and longevity.
In another prior system the moveable mechanical plates have been eliminated and the dart board is formed of multiple, sandwiched layers of alternating conductive and insulative materials. When the metal tip of a dart is embedded in a scoring segment or area, it pierces and electrically connects two such conductive layers completing a circuit between them to indicate the location of the dart. Examples of such systems are shown in U.S. Pat. No. 4,244,583 (WOOD et al.) and published UK Patent Application No. 2,030,877. A principal disadvantage of the latter systems is their reduced longevity due to the deterioration of the scoring segments after repeated piercing.
Various systems have also been proposed in which transmitting and receiving antennae are provided for the transmission of electromagnetic signals, and in which one of the antennae is formed by treating or otherwise coating the conventional sisal fibers of a conventional dart board so as to render the fibers electrically conductive to form one of these antennae. In these conductive fiber systems, when a metal tipped dart is embedded in the conductive fibers, the dart itself becomes a part of the antenna in which it is embedded and, thereby, increases the signal strength of either the received or transmitted signal depending upon the function of the conductive material in which the dart is embedded. Examples of these systems are shown in U.S. Pat. Nos. 4,678,198 (BOWYER et al.) and 5,462,283 (ALLEN). Some of the disadvantages of these systems are their low scoring reliability and/or difficulty of placement or overall size of at least one of the antennae.
Still other systems have relied upon the generation of electromagnetic fields utilizing individual coils fixed adjacent the respective scoring areas. When a dart having the ability to affect the electromagnetic activity is embedded in one of the areas, the field generated by the coil is altered and the alteration is detected to indicate the presence and location of the dart. Examples of these systems are described in German Utility Model G 88 06 580.4 and published UK Patent Application No. 2,086,243. One of the disadvantages of these systems is that they are complex and cumbersome due to the need for placement and energization of the numerous and space consuming electromagnetic coils.
More recently a system has also been proposed which like some of the prior systems can utilize a conventional sisal fiber dart board, but which avoids the need to coat or otherwise treat the fibers with an electrically conductive compound, and which relies on a principle of interference with electromagnetic radiation by an embedded dart, rather than the dart acting as part of a transmitting/receiving electromagnetic radiation antenna. An example of such system is shown in published PCT Application No. W095/04251. Although this system enjoys a number of advantages over the prior systems earlier described herein, there is still room for improvement in reliability, simplicity and reduction in manufacturing ease and expense.
A system incorporating the principles of the present invention for automatically detecting and locating a missile embedded in a target, such as a dart in a dart board, enjoys one or more advantages over the aforementioned systems of the prior art. One such advantage is that the system of the present invention is simple, and is easier and less expensive to construct and assemble than many of the systems of the prior art. In the system of the present invention, an antenna is positioned on the back of the target so that it can be essentially equidistant to all of the scoring segments on the front of the target. This results in substantially improved reliability and simplicity, eliminates the need for an antenna external to the dart board, and in the case of the prior systems which required the spacing of an antenna peripherally of the dart board scoring area, reduces the size of the overall game assembly. Positioning of the antenna at the back of the dart board also substantially reduces the power needed from the signal generator. In addition, the system of the present invention enjoys an order of magnitude of improvement in reliability which will insure that even where darts are embedded in a scoring segment closely adjacent the next scoring segment, the location of the dart in the proper and correct segment will be easily discriminated and accurately read virtually all of the time.
In one principal aspect of the present invention, a system is provided for detecting and locating a missile embedded in a target having a front face with a plurality of target areas formed of a first material into which first material one or more of the missiles may be selectively embedded from the front face of the target. A first electrically conductive area is located in the target areas and adjacent the front face, and a back is provided on the target opposite the front face. A second electrically conductive area is positioned adjacent the back, and the second electrically conductive area is spaced and electrically separated from the first electrically conductive area. A signal generator imparts a signal to one of the aforementioned conductive areas whereby that one of the conductive areas defines a transmitting antenna for an electromagnetic signal corresponding to the signal imparted to the one conductive area. The other of the conductive areas defines a receiving antenna for the electromagnetic signal which is transmitted from the transmitting antenna. A processor is electrically connected to the other of the conductive areas and distinguishes between a first electromagnetic signal which is received and sensed by the other of the conductive areas in the absence of a missile in a given target area, and a second electromagnetic signal which is an alteration of the first electromagnetic signal by the presence of a missile in the given target area to permit the detection of the presence and location of the missile.
In another principal aspect of the present invention, the first material comprises dart board bristles and the first electrically conductive area comprises a conductive coating on the bristles.
In still another principal aspect of the present invention, the aforementioned bristles have a given depth, and the first electrically conductive area is located within that bristle depth adjacent to the front face of the target and extends for a depth into the bristles which is less than the given depth.
In still another principal aspect of the present invention, the system includes an electrically insulative barrier extending into the first material for a depth greater than the depth of the first electrically conductive area, and the insulative barrier defines the plurality of target areas and electrically divides and separates the first electrically conductive areas of adjacent target areas from each other.
In still another principal aspect of the present invention, the second electrically conductive area adjacent the back of the target is an electrically conductive plate and, more preferably, one which is painted onto the target back.
In still another principal aspect of the present invention, the system includes still another electrically conductive plate in addition to the last mentioned plate adjacent to the back, and an insulative material electrically separates the two conductive plates.
In still another principal aspect of the present invention, an electrically conductive pin is coupled to the first conductive area so as to substantially increase the electromagnetic signal in the first conductive area.
In still another principal aspect of the present invention, the first electrically conductive area is the receiving antenna and the second electrically conductive area is the transmitting antenna which transmits the electromagnetic signal from the back of the target to the receiving antenna at the front face of the target and to a missile when the missile is embedded in the first material.
In still another principal aspect of the present invention, the missile is a dart and the target is a dart board.
These and other objects, features and advantages of the present invention will be more clearly understood through a consideration of the following detailed description.